Mountains of shifting sand swirl around the feet of the rugged Sangre de Cristo Mountains in Southern Colorado. Rising over 750 feet, the dunes are the largest sand dunes in North America. On Monday, September 13, 2004, they became part of the newest national park in the United States. The new Great Sand Dunes National Park contains more than sand—the 84,670-acre park also includes mountain lakes and tundra, high mountain peaks, pine and spruce forests, stands of aspen, grassland, and wetlands.

This natural color image, acquired by the Landsat Enhanced Thematic Mapper plus (EMT+) on October 14, 1999, shows the park and its immediate surroundings. To the west of the Sangre de Cristo Mountains is a vast sand field, which extends beyond the left edge of this image. As the wind blow east over the plain, it picks up the sand. Like snow drifting behind a snow fence, the blowing sand is blocked by the mountains and accumulates at their base. Over years, the loose sand has built into massive dunes, which are clearly visible in this image. The dune field forms a light, almost white crescent immediately west of the mountains. The darker sands of the sand field are largely anchored in place by grass and other low plants.

Southwest of the dune fields, on the lower left edge of the image, are the San Luis Lakes. The lakes are just beyond the western border of Great Sand Dunes National Park. The southern border of the park is also visible in this image. It is formed by Highway 6, the straight light line running across the lower edge of the image. The eastern edge of the park extends into the mountains and the northern border is near Sand Creek, the jagged dark brown line across the top of the image.

These boundaries were largely in place as part of the former Great Sand Dunes National Monument. The National Monument was established in 1932. In becoming a National Park Complex, Great Sand Dunes will eventually expand to 140,000 acres as it incorporates the Baca National Wildlife Refuge on its northwest edge and the Great Sand Dunes National Preserve on the northeast. For more information about the park, please visit the National Park Service.